Vapor electric device



June 20, 1950 w. E. PAKALA ETAL 7 VAPOR ELECTRIC DEVICE Filed March 26, 1949 Insulation K wi? vi 1 'INVENTORS MA William E.Pokulo and /V HerbertA Rose- WIM ATTORNEY WITNESSES:

Patented June 20, 1950 VAPOR ELECTRIC DEVICE WillialnrE. Pakala, Forest A. Rose, Seattle, Wash house Electric Corpor Hills, Pa., and Herbert assignors to Westingation,

East Pittsburgh,

Pa.;. a corporation of Pennsylvania Application March 26, 1949, Serial No. 83,612

4 Claims.

Our invention relates to vapor-electric device and particularly to a vapor-electric v-alve capable of withstanding rapidly applied potentials between the anode and cathode.

It is frequently desirable to use vapor-electric valves to convert direct current to alternating current or alternating current of one frequency to alternating current of another frequency and while it is substantially impossible to terminate an electric arc in a vapor-electric device without reversing the polarity applied to the device, it is now customary to provide oscillator circuits which momentarily reverse the potential or stop the current flow so that any desired frequency of output may be attained either from direct current or from alternating current of any frequency. However, considerable diffioultv has been experienced by reignition of the arc in the device upon the application of potential before the ionization has disappeared in the valves.

According to our invention, we provide a valve having, in addition to the normal control grids present in conversion tubes, at least a pair of deionizing grids one of which is placed in closely spaced proximity to the control grid and the other close to the anode surface so that the ionization produced by the arc in the valve will be rapidly dissipated so that the appearance of potential between the anode and cathode will find the ions at the anode and cathode so thoroughly dissipated that spontaneous ignition of a cathode spot at either electrode is substantially prevented.

It is accordingly an object of our invention to provide a vapor-electric valve having a high deionization rate.

It is a, further object of our invention to provide an electric valve through which a potential may be rapidly reapplied after a conducting interval.

It is a, further object of our invention to provide a vapor-electric valve having deionizing grids in proximity to each of the major electrodes in the device.

Other objects and advantages of our invention will be apparent from the following detailed description taken in conjunction with the accompanying drawing, in which the figure is a sectional elevation of a vapor-electric valve embodying our invention.

In the exemplary embodiment of our invention, the vapor-electric valve comprises a metallic container I having a cooling means such as a water jacket 2 applied to the exterior surface of at least a portion of the container I to provide a cooled condensing surface 3 on the interior of the container wall. A pool 4 of cathode material, such as mercury, is retained in the bottom portion of the container l and the anode 5, usually of graphite, is supported in spaced insulated relation by means of an anode stem 6 mounted in a lead-in bushing 1 attached to the top header 8 of the container I.

A make-alive or ignitor I0 is provided in contact with the cathode pool 4 for initiating a cathode spot at desired intervals on the cathode. The anode 5 is surrounded on the sides and the back by an anode shield ll supported from the top header 8 of th container I by means of a plurality of insulating bushings l2. The open end of the anode shield H is provided with a control electrode l3 which is closely spaced adjacent the operating face M of the anode 5. Control potential is applied to the grid l3 from any suitable source through a lead-in connection usually provided in the header 8 and connected to the anode shield II.

In order to deionize the space immediately adjacent the control electrode l3, a deionizing grid It is placed in proximity to the controller grid l3 and is usually supported by a metallic cylinder ll also attached in insulated relation to the container, preferably by means of the same insulating bushings l2 that support the anode shield II. If desired, potentials of various kinds may also be applied to the deionizing grid by means of a lead-in bushing l8 attached in insulating relation to the container header 8.

A second deionizing grid 20 was placed immediately above the surface of the cathode pool 4 and is preferably supported by means of rods or strips 2| attached to the cylinder l1 supporting the firstmentioned deionizing grid IS. The rods or strips 2i are used so that the space between the deionizing grids l6 and 20 is open to the condensing surface 3 or cooled side wall of the container I so vapor between the deionizing grids may have free access to the condensing surface 3 and not only reduce the vapor pressure but materially deenergize the space between the grids l6 and 20.

The deionizing grid 20 adjacent the cathode surface is provided with a plurality of openings 22 which is directed away from the line of passage between the anode 5 and the cathode 4 so that the vapor and any droplets thrown off from the oathode surface will be deflected away from the anode 5 and toward the condensing surfacesv 3.

In the operation of the device according to our invention, a cathode spot will be established at the beginning of the conducting interval and will 3 be maintained by a suitable potential applied usually to the deionizing grid 20 which acts then as a keep-alive electrode for a predetermined interval. Control potentials of the desired frequency are applied to the control electrode l3 so that current then can pick up from the main anode 5 to the cathode l and will flow as long as the current conditions of the circuit permit.

When the circuit conditions terminate current flow the deionizing grids l6 and will rapidly reduce the ionization adjacent the anode 5 or control electrode [3 and the cathode surface so that the reapplication of a potential between the anode 5 and cathode 4 will not automatically restrike but must await the control action of the control rid l3. V

We have found that with a spacing of the order of one-half inch between the deionizing grid and the cathode surface, that the ionization will be reduced below the danger valuein a time of the order of 65 micro-seconds and a tube Withjthese characteristics willwork at a frequency of approximately 3,000 cycles without premature restriking because of the ionization present.

While for purposes of illustration, we have shown a specific embodiment of our invention and described the same to the best of our present ability, we wish it to be understood thatthis is illustrative only and that many changes andmodifications can be made therein Without departing from the true spirit of our invention or the scope of the appended .claims.

, We claim as our invention? 1.. A vapor-electricdischarge device comprising a container, means. for cooling thewallsof said containena cathode pool in said container, an anode supported in spaced insulated relation to said cathode pool, a shield enclosing the sides and back of said anode, a control grid adjacent the face of the anode, a deionizing grid adjacent said control grid, a second deionizing grid adjacent the cathode pool, the grid passages of said cathode grid being inclined relative to the direction between anode and cathode. 2. 'A vapor-electric device comprising a container, a cathode pool in said container, an anode spaced from said pool, means for cooling the side walls of said container to provide a condensing surface, a. cathode grid closely spaced with respect to the surface of the cathode pool, an anode grid closely spaced with respect to the surface of the anode, the space between said anode and cathode grid being substantially greater than the distance between said cathode and said grid, said space being substantially open to the condensing surface.

3. A vapor electric valve for operation at high frequency comprising a container, a vaporizable cathode in said container, an anode in spaced insulating relation in said container, a control grid closely spaced from said anode, a pair of deionizing grids between said control grid and said cathode, one of said deionizing grids being closely spaced with respect to said control grid, the other deionizing grid being closely spaced with respect to the cathode surface, metallic supports between said deionizing grids, the surface area of said supports being small in respect to the lateral area between said deionizing grids.

4. A high-frequency vapor-electric device comprising a container, means cooling the side walls of said container, a pool of cathode material in said container, an anode in spaced insulated relation to said pool, a control grid adjacent the face of the anode, a pair of deionizing grids interposed between said control grid and the surface of the pool, said pair of deionizing grids being widely spaced from each other, said deionizing grid adjacent the cathode being spaced from the pool surface a distance of the order of one-half inch.

WILLIAM E. PAKALA. HERBERT A. ROSE.

REFERENCES CITED The following references are of record in the file of this patent: 1

UNITED STATES PATENTS Number Name M I Date 2,454,129 Boyer et a1. Nov. 16, 1948 2,465,200 Colaiace et al Mar. 22, 1949 

